RFA: PACKET_OVERHEAD constant added to remote.c

[Kevin Buettner <kevinb at cygnus dot com>]

Hi Andrew,

Jesper Skov alerted me to the fact that we were getting some "Remote
packet too long" messages when attempting to debug using a gdbserver
for i386 linux.  The problem was that the memory packet size
computations were not taking into account the packet overhead.  This
would've been a one line fix, but I decided to define PACKET_OVERHEAD
instead of adding another hard-coded instance of the constant 32.

Kevin


	* remote.c (PACKET_OVERHEAD): Define.
	(get_memory_packet_size): Take PACKET_OVERHEAD into account when
	computing memory packet size.
	(build_remote_packet_sizes): Use PACKET_OVERHEAD instead of
	hard-coded constants.

Index: remote.c
===================================================================
RCS file: /cvs/cvsfiles/devo/gdb/remote.c,v
retrieving revision 1.258
diff -u -r1.258 remote.c
--- remote.c	1999/11/08 13:14:17	1.258
+++ remote.c	1999/11/12 17:57:13
@@ -315,6 +315,11 @@
 /* compatibility. */
 #define PBUFSIZ (remote_packet_size)
 
+/* Overhead for packet header / footer.  NOTE: cagney/1999-10-26: I suspect
+   that 8 (``$NN:G...#NN'') is a better guess, the below has been padded a
+   little. */
+#define PACKET_OVERHEAD 32
+
 /* User configurable variables for the number of characters in a
    memory read/write packet.  MIN (PBUFSIZ, g-packet-size) is the
    default.  Some targets need smaller values (fifo overruns, et.al.)
@@ -358,7 +363,7 @@
     }
   else
     {
-      what_they_get = remote_packet_size;
+      what_they_get = remote_packet_size - PACKET_OVERHEAD;
       /* Limit the packet to the size specified by the user. */
       if (config->size > 0
 	  && what_they_get > config->size)
@@ -502,12 +507,9 @@
   remote_packet_size = 400;
   /* Should REGISTER_BYTES needs more space than the default, adjust
      the size accordingly. Remember that each byte is encoded as two
-     characters. 32 is the overhead for the packet header /
-     footer. NOTE: cagney/1999-10-26: I suspect that 8
-     (``$NN:G...#NN'') is a better guess, the below has been padded a
-     little. */
-  if (REGISTER_BYTES > ((remote_packet_size - 32) / 2))
-    remote_packet_size = (REGISTER_BYTES * 2 + 32);
+     characters.  */
+  if (REGISTER_BYTES > ((remote_packet_size - PACKET_OVERHEAD) / 2))
+    remote_packet_size = (REGISTER_BYTES * 2 + PACKET_OVERHEAD);
   
   /* This one is filled in when a ``g'' packet is received. */
   actual_register_packet_size = 0;